This invention relates to a modem and a modem signalling protocol especially suited for use with wireless communication equipment. A described method of modulation of digital data is especially suited for use with conventional two-way FM radios.
The transmission of digital data over a radio link has been accomplished by the use of 202 modems which provide direct audio frequency shift keying (FSK) to the normal audio input of a two-way radio. The use of 202 modems in such a system requires no special signalling protocol considerations since the substitution of radios for the normal wireline communication channel does not disrupt the normal tone signalling.